Snow Leopard is an upgrade from Leopard, and as the name suggests it's not an overhaul but a refinement.

While in recent years software upgrades have meant piling features upon features, Pogue explains that Apple, with Snow Leopard, and Microsoft, with Windows 7, are taking a new tack this year with "operating systems that are unapologetically billed as cleaned-up, slimmed-down versions of what came before."

Pogue found Snow Leopard to start up faster than Leopard (72 seconds versus 100 seconds), open programs faster ("Web browser, 3 seconds; calendar, 5 seconds; iTunes, 7 seconds") and still the time to be halved when a program was opened for a second time.

Both critics also enjoyed its slim size. "One delightful change: Snow Leopard takes up less than half the room on a hard disk that Leopard did, and Apple says the average user who upgrades will free up about 7 gigabytes of space," wrote Mossberg. "On my 2008-vintage MacBook Pro, I gained back a whopping 14 gigabytes."

Despite the Apple engineers' insistence that with Snow Leopard they were just tidying up a bit, both critics were appreciative of the gobs of new features they discovered.

"The Mac adjusts its own clock when you travel, just like a cellphone. The menu bar can now show the date, not just the day of the week. The menu of nearby wireless hot spots now shows the signal strength for each. When you're running Windows on your Mac, you can now open the files on the Macintosh side' without having to restart. Icons can now be 512 pixels (several inches) square, turning any desktop window into a light table for photos," Pogue wrote, describing a few.

Another big change is the switch to the backward-compatible 64-bit software standard, from the 32-bit one, which both enjoyed for the speed it brought.

Perhaps the biggest new feature of all, wrote Mossberg, is Snow Leopard's compatibility with Microsoft Exchange. While even Windows users have to buy add-on software to make their PCs jibe with Exchange, with Snow Leopard, Macs now have that capability built in.

"With the generous help of my company's IT folks, I tested this feature, and it worked very well. All my corporate information flowed into Apple's programs, very quickly, and I could search the company directory, check the calendars of people with whom I wished to schedule meetings, and more."

However, he added, "Apple makes setting up this new feature look simpler than it is."

Overall, Mossberg found Snow Leopard's price to be appropriate for a software that proposes to offer simply a boost up from its pricier predecessor. And while he enjoyed it, he found the upgrade - which he said opens jam-packed e-mail folders almost instantly, includes a built-in QuickTime function that lets users make a video of their desktop actions, and which costs roughly the price of two cocktails in Manhattan - not to be a "must have."

"It's more of a nice-to-have upgrade. If you're happy with Leopard, there's no reason to rush out and get Snow Leopard," Mossberg wrote.

Pogue found the update to be more of a deal. "If you're already running Leopard, paying the $30 for Snow Leopard is a no-brainer," he wrote.